Recover Data from Unmount ASM Diskgroup(without Backup)

DB Has NO Regular RMAN Backups, Recent Archivelogs Are Available

We cannot restore datafiles from an RMAN backupset. We use AMDU to extract the datafile from the diskgroup. 

1. Use AMDU to report on metadata from the unmountable disk group.

View the report produced for corruptions or any issues.

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$ amdu -diskstring '/dev/asm-disk4' -dump TEST amdu_2016_05_25_14_25_22/   $ ls -lrt ./amdu_2016_05_25_14_25_22/ total 52244 -rw-r--r--. 1 oracle oinstall     4240 May 25 14:25 TEST.map -rw-r--r--. 1 oracle oinstall 53485568 May 25 14:25 TEST_0001.img -rw-r--r--. 1 oracle oinstall     2981 May 25 14:25 report.txt   $ cat report.txt -*-amdu-*- ******************************* AMDU Settings ******************************** ORACLE_HOME = /u01/app/12.1.0.2/grid System name:    Linux Machine:        x86_64 amdu run:       25-MAY-16 14:25:22 Endianess:      1 ... ************************** SCANNING DISKGROUP TEST *************************** ---------------------------- SCANNING DISK N0001 ----------------------------- Disk N0001: '/dev/asm-disk4' ------------------------- SUMMARY FOR DISKGROUP TEST ------------------------- Allocated AU's: 53 Free AU's: 5061 AU's read for dump: 53 Block images saved: 13058 Map lines written: 53 Heartbeats seen: 0 Corrupt metadata blocks: 0 Corrupt AT blocks: 0

2. Use AMDU to extract the datafiles from the unmountable disk group.

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$ amdu -diskstring '/dev/asm-disk4' -extract TEST.256 amdu_2016_05_25_15_30_12/   $ ls -lrth ./amdu_2016_05_25_15_30_12 total 11M -rw-r--r--. 1 oracle oinstall  11M May 25 15:30 TEST_256.flt -rw-r--r--. 1 oracle oinstall 3.7K May 25 15:30 report.txt

3. Rename the datafile in the controlfile to point to the AMDU extracted datafiles, apply recovery and open the database.

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SQL> startup mount SQL> alter database open; alter database open * ERROR at line 1: ORA-01157: cannot identify/lock data file 15 - see DBWR trace file ORA-01110: data file 15: '+TEST/CDBRAC/DATAFILE/test_tbs.256.912785223'   SQL> alter database rename file '+TEST/CDBRAC/DATAFILE/test_tbs.256.912785223' to '/home/oracle/extract/amdu_2016_05_25_15_30_12/TEST_256.f'; Database altered.   SQL> recover datafile 15; Media recovery complete.   SQL> alter database open; Database altered.